Water - Mackenzie

Gemfile.lock

@@ -0,0 +1,36 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ansi (1.5.0)
+    builder (3.2.4)
+    coderay (1.1.3)
+    method_source (1.0.0)
+    minitest (5.14.2)
+    minitest-reporters (1.4.2)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    minitest-skip (0.0.3)
+      minitest (~> 5.0)
+    minitest-spec (0.0.2.1)
+      minitest (>= 3.0)
+    pry (0.13.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    rake (13.0.1)
+    ruby-progressbar (1.10.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  minitest
+  minitest-reporters
+  minitest-skip
+  minitest-spec
+  pry
+  rake
+
+BUNDLED WITH
+   2.1.4

lib/hourglass.rb

@@ -1,4 +1,21 @@
 
 def hourglass(matrix)
-  raise NotImplementedError, "The matrix method has not been implemented yet!"
+  # i is top left row coordinate
+  # j is top left column coordinate
+
+  max_sum = (-1.0 / 0.0)
+  i = 0
+
+  until (i + 2) == (matrix.length) do
+    j = 0
+    until (j + 2) == (matrix[0].length) do
+      if  (matrix[i][j] + matrix[i][j+1] + matrix[i][j+2] + matrix[i+1][j+1] + matrix[i+2][j] + matrix[i+2][j+1] + matrix[i+2][j+2]) > max_sum
+        max_sum = matrix[i][j] + matrix[i][j+1] + matrix[i][j+2] + matrix[i+1][j+1] + matrix[i+2][j] + matrix[i+2][j+1] + matrix[i+2][j+2]
+      end
+      j += 1
+    end
+    i += 1
+  end
+
+  return max_sum
 end